The present invention relates to gas refrigerators and more particularly to a Kirk-cycle gas refrigerator in which rod members are utilized to effect volumetric changes of a refrigerating medium so that an extremely low temperature can be produced.
Conventionally, in such Kirk-cycle gas refrigerators, the rod member is mechanically connected to a piston provided in a volume-variable space. Thus, the cryogenic section is mechanically connected to the driving section so that mechanical vibrations produced in the driving section are transmitted to the cryogenic section.
This, however, has the tendency to sometimes cause problems, particularly in the case where the apparatus is used as a cryopump. Further, the apparatus becomes very large in relation to the cryo-section so that handling of the apparatus becomes difficult as well as inconvenient.